In the field of hearing devices, and in particular of hearing-aid devices, noise cancelling is an important issue, because background noise greatly damages speech intelligibility for a user of a hearing device.
One known way of cancelling noise in a signal composed of a desired signal plus an unwanted signal (noise signal), which interferes with said desired signal, makes use of an adaptive filter, which is a filter that keeps adjusting itself. A corresponding a noise canceller is referred to as adaptive noise canceller.
From “Noise reduction in hearing aids: An overview”, Harry Levitt, Journal of Rehabilitation Research and Development, Vol. 38 No. 1, January/February 2001, p. 111-121, an adaptive noise canceller is known, which receives at one input a signal from a speech-and-noise microphone and at another input a signal from a noise microphone. The signal from said noise microphone is fed to an adaptive filter and subtracted from the signal from said speech-and-noise microphone. Thereupon, the adaptive noise canceller can output a signal, which is close to the desired speech signal (speech, with noise subtracted, at least approximately).
Many adaptive filters are known in the art and used for noise cancelling. The LMS (least means square) adaptive filtering algorithm, for example, has been developed more than 45 years ago by Widrow and Hoff.
It is desirable to provide for an improved noise cancellation.